sidebar_position: 9 title: “Matrix” description: “Set up Hermes Agent as a Matrix bot”

Matrix Setup

Hermes Agent integrates with Matrix, the open, federated messaging protocol. Matrix lets you run your own homeserver or use a public one like matrix.org — either way, you keep control of your communications. The bot connects via the mautrix Python SDK, processes messages through the Hermes Agent pipeline (including tool use, memory, and reasoning), and responds in real time. It supports text, file attachments, images, audio, video, and optional end-to-end encryption (E2EE).

Hermes works with any Matrix homeserver — Synapse, Conduit, Dendrite, or matrix.org.

Before setup, here’s the part most people want to know: how Hermes behaves once it’s connected.

How Hermes Behaves

:::tip The bot automatically joins rooms when invited. Just invite the bot’s Matrix user to any room and it will join and start responding.

::

Session Model in Matrix

By default:

• each DM gets its own session
• each thread gets its own session namespace
• each user in a shared room gets their own session inside that room

This is controlled by config.yaml:

group_sessions_per_user: true

Set it to false only if you explicitly want one shared conversation for the entire room:

group_sessions_per_user: false

Shared sessions can be useful for a collaborative room, but they also mean:

• users share context growth and token costs
• one person’s long tool-heavy task can bloat everyone else’s context
• one person’s in-flight run can interrupt another person’s follow-up in the same room

Mention and Threading Configuration

You can configure mention and auto-threading behavior via environment variables or config.yaml:

matrix:
  require_mention: true           # Require @mention in rooms (default: true)
  free_response_rooms:            # Rooms exempt from mention requirement
    - "!abc123:matrix.org"
  auto_thread: true               # Auto-create threads for responses (default: true)
  dm_mention_threads: false       # Create thread when @mentioned in DM (default: false)

Or via environment variables:

MATRIX_REQUIRE_MENTION=true
MATRIX_FREE_RESPONSE_ROOMS=!abc123:matrix.org,!def456:matrix.org
MATRIX_AUTO_THREAD=true
MATRIX_DM_MENTION_THREADS=false

:::note If you are upgrading from a version that did not have MATRIX_REQUIRE_MENTION, the bot previously responded to all messages in rooms. To preserve that behavior, set MATRIX_REQUIRE_MENTION=false.

::

This guide walks you through the full setup process — from creating your bot account to sending your first message.

Step 1: Create a Bot Account

You need a Matrix user account for the bot. There are several ways to do this:

Option A: Register on Your Homeserver (Recommended)

If you run your own homeserver (Synapse, Conduit, Dendrite):

1. Use the admin API or registration tool to create a new user:

# Synapse example
register_new_matrix_user -c /etc/synapse/homeserver.yaml http://localhost:8008

2. Choose a username like hermes — the full user ID will be @hermes:your-server.org.

Option B: Use matrix.org or Another Public Homeserver

1. Go to Element Web and create a new account.
2. Pick a username for your bot (e.g., hermes-bot).

Option C: Use Your Own Account

You can also run Hermes as your own user. This means the bot posts as you — useful for personal assistants.

Step 2: Get an Access Token

Hermes needs an access token to authenticate with the homeserver. You have two options:

Option A: Access Token (Recommended)

The most reliable way to get a token:

Via Element:

1. Log in to Element with the bot account.
2. Go to Settings → Help & About.
3. Scroll down and expand Advanced — the access token is displayed there.
4. Copy it immediately.

Via the API:

curl -X POST https://your-server/_matrix/client/v3/login \
  -H "Content-Type: application/json" \
  -d '{
    "type": "m.login.password",
    "user": "@hermes:your-server.org",
    "password": "your-password"
  }'

The response includes an access_token field — copy it.

::warning[Keep your access token safe] The access token gives full access to the bot’s Matrix account. Never share it publicly or commit it to Git. If compromised, revoke it by logging out all sessions for that user.

::

Option B: Password Login

Instead of providing an access token, you can give Hermes the bot’s user ID and password. Hermes will log in automatically on startup. This is simpler but means the password is stored in your .env file.

MATRIX_USER_ID=@hermes:your-server.org
MATRIX_PASSWORD=your-password

Step 3: Find Your Matrix User ID

Hermes Agent uses your Matrix User ID to control who can interact with the bot. Matrix User IDs follow the format @username:server.

To find yours:

1. Open Element (or your preferred Matrix client).
2. Click your avatar → Settings.
3. Your User ID is displayed at the top of the profile (e.g., @alice:matrix.org).

:::tip Matrix User IDs always start with @ and contain a : followed by the server name. For example: @alice:matrix.org, @bob:your-server.com.

::

Step 4: Configure Hermes Agent

Option A: Interactive Setup (Recommended)

Run the guided setup command:

hermes gateway setup

Select Matrix when prompted, then provide your homeserver URL, access token (or user ID + password), and allowed user IDs when asked.

Option B: Manual Configuration

Add the following to your ~/.hermes/.env file:

Using an access token:

# Required
MATRIX_HOMESERVER=https://matrix.example.org
MATRIX_ACCESS_TOKEN=***

# Optional: user ID (auto-detected from token if omitted)
# MATRIX_USER_ID=@hermes:matrix.example.org

# Security: restrict who can interact with the bot
MATRIX_ALLOWED_USERS=@alice:matrix.example.org

# Multiple allowed users (comma-separated)
# MATRIX_ALLOWED_USERS=@alice:matrix.example.org,@bob:matrix.example.org

Using password login:

# Required
MATRIX_HOMESERVER=https://matrix.example.org
MATRIX_USER_ID=@hermes:matrix.example.org
MATRIX_PASSWORD=***

# Security
MATRIX_ALLOWED_USERS=@alice:matrix.example.org

Optional behavior settings in ~/.hermes/config.yaml:

group_sessions_per_user: true

• group_sessions_per_user: true keeps each participant’s context isolated inside shared rooms

Start the Gateway

Once configured, start the Matrix gateway:

hermes gateway

The bot should connect to your homeserver and start syncing within a few seconds. Send it a message — either a DM or in a room it has joined — to test.

::tip You can run hermes gateway in the background or as a systemd service for persistent operation. See the deployment docs for details.

::

End-to-End Encryption (E2EE)

Hermes supports Matrix end-to-end encryption, so you can chat with your bot in encrypted rooms.

Requirements

E2EE requires the mautrix library with encryption extras and the libolm C library:

# Install mautrix with E2EE support
pip install 'mautrix[encryption]'

# Or install with hermes extras
pip install 'hermes-agent[matrix]'

You also need libolm installed on your system:

# Debian/Ubuntu
sudo apt install libolm-dev

# macOS
brew install libolm

# Fedora
sudo dnf install libolm-devel

Enable E2EE

Add to your ~/.hermes/.env:

MATRIX_ENCRYPTION=true

When E2EE is enabled, Hermes:

• Stores encryption keys in ~/.hermes/platforms/matrix/store/ (legacy installs: ~/.hermes/matrix/store/)
• Uploads device keys on first connection
• Decrypts incoming messages and encrypts outgoing messages automatically
• Auto-joins encrypted rooms when invited

Cross-Signing Verification (Recommended)

If your Matrix account has cross-signing enabled (the default in Element), set the recovery key so the bot can self-sign its device on startup. Without this, other Matrix clients may refuse to share encryption sessions with the bot after a device key rotation.

MATRIX_RECOVERY_KEY=EsT... your recovery key here

Where to find it: In Element, go to Settings → Security & Privacy → Encryption → your recovery key (also called the “Security Key”). This is the key you were asked to save when you first set up cross-signing.

On each startup, if MATRIX_RECOVERY_KEY is set, Hermes imports cross-signing keys from the homeserver’s secure secret storage and signs the current device. This is idempotent and safe to leave enabled permanently.

::warning If you delete the ~/.hermes/platforms/matrix/store/ directory, the bot loses its encryption keys. You’ll need to verify the device again in your Matrix client. Back up this directory if you want to preserve encrypted sessions.

::

::info If mautrix[encryption] is not installed or libolm is missing, the bot falls back to a plain (unencrypted) client automatically. You’ll see a warning in the logs.

::

Home Room

You can designate a “home room” where the bot sends proactive messages (such as cron job output, reminders, and notifications). There are two ways to set it:

Using the Slash Command

Type /sethome in any Matrix room where the bot is present. That room becomes the home room.

Manual Configuration

Add this to your ~/.hermes/.env:

MATRIX_HOME_ROOM=!abc123def456:matrix.example.org

:::tip To find a Room ID: in Element, go to the room → Settings → Advanced → the Internal room ID is shown there (starts with !).

::

Troubleshooting

Bot is not responding to messages

Cause: The bot hasn’t joined the room, or MATRIX_ALLOWED_USERS doesn’t include your User ID.

Fix: Invite the bot to the room — it auto-joins on invite. Verify your User ID is in MATRIX_ALLOWED_USERS (use the full @user:server format). Restart the gateway.

“Failed to authenticate” / “whoami failed” on startup

Cause: The access token or homeserver URL is incorrect.

Fix: Verify MATRIX_HOMESERVER points to your homeserver (include https://, no trailing slash). Check that MATRIX_ACCESS_TOKEN is valid — try it with curl:

curl -H "Authorization: Bearer YOUR_TOKEN" \
  https://your-server/_matrix/client/v3/account/whoami

If this returns your user info, the token is valid. If it returns an error, generate a new token.

“mautrix not installed” error

Cause: The mautrix Python package is not installed.

Fix: Install it:

pip install 'mautrix[encryption]'

Or with Hermes extras:

pip install 'hermes-agent[matrix]'

Encryption errors / “could not decrypt event”

Cause: Missing encryption keys, libolm not installed, or the bot’s device isn’t trusted.

Fix:

1. Verify libolm is installed on your system (see the E2EE section above).
2. Make sure MATRIX_ENCRYPTION=true is set in your .env.
3. In your Matrix client (Element), go to the bot’s profile -> Sessions -> verify/trust the bot’s device.
4. If the bot just joined an encrypted room, it can only decrypt messages sent after it joined. Older messages are inaccessible.

Upgrading from a previous version with E2EE

If you previously used Hermes with MATRIX_ENCRYPTION=true and are upgrading to a version that uses the new SQLite-based crypto store, the bot’s encryption identity has changed. Your Matrix client (Element) may cache the old device keys and refuse to share encryption sessions with the bot.

Symptoms: The bot connects and shows “E2EE enabled” in the logs, but all messages show “could not decrypt event” and the bot never responds.

What’s happening: The old encryption state (from the previous matrix-nio or serialization-based mautrix backend) is incompatible with the new SQLite crypto store. The bot creates a fresh encryption identity, but your Matrix client still has the old keys cached and won’t share the room’s encryption session with a device whose keys changed. This is a Matrix security feature – clients treat changed identity keys for the same device as suspicious.

Fix (one-time migration):

1. Generate a new access token to get a fresh device ID. The simplest way:

   curl -X POST https://your-server/_matrix/client/v3/login \
     -H "Content-Type: application/json" \
     -d '{
       "type": "m.login.password",
       "identifier": {"type": "m.id.user", "user": "@hermes:your-server.org"},
       "password": "***",
       "initial_device_display_name": "Hermes Agent"
     }'
   

   Copy the new access_token and update MATRIX_ACCESS_TOKEN in ~/.hermes/.env.

2. Delete old encryption state:

   rm -f ~/.hermes/platforms/matrix/store/crypto.db
   rm -f ~/.hermes/platforms/matrix/store/crypto_store.*
   

3. Set your recovery key (if you use cross-signing — most Element users do). Add to ~/.hermes/.env:

   MATRIX_RECOVERY_KEY=EsT... your recovery key here
   

   This lets the bot self-sign with cross-signing keys on startup, so Element trusts the new device immediately. Without this, Element may see the new device as unverified and refuse to share encryption sessions. Find your recovery key in Element under Settings → Security & Privacy → Encryption.

4. Force your Matrix client to rotate the encryption session. In Element, open the DM room with the bot and type /discardsession. This forces Element to create a new encryption session and share it with the bot’s new device.

5. Restart the gateway:

   hermes gateway run
   

   If MATRIX_RECOVERY_KEY is set, you should see Matrix: cross-signing verified via recovery key in the logs.

6. Send a new message. The bot should decrypt and respond normally.

:::note After migration, messages sent before the upgrade cannot be decrypted – the old encryption keys are gone. This only affects the transition; new messages work normally.

::

::tip New installations are not affected. This migration is only needed if you had a working E2EE setup with a previous version of Hermes and are upgrading.

Why a new access token? Each Matrix access token is bound to a specific device ID. Reusing the same device ID with new encryption keys causes other Matrix clients to distrust the device (they see changed identity keys as a potential security breach). A new access token gets a new device ID with no stale key history, so other clients trust it immediately.

::

Sync issues / bot falls behind

Cause: Long-running tool executions can delay the sync loop, or the homeserver is slow.

Fix: The sync loop automatically retries every 5 seconds on error. Check the Hermes logs for sync-related warnings. If the bot consistently falls behind, ensure your homeserver has adequate resources.

Bot is offline

Cause: The Hermes gateway isn’t running, or it failed to connect.

Fix: Check that hermes gateway is running. Look at the terminal output for error messages. Common issues: wrong homeserver URL, expired access token, homeserver unreachable.

“User not allowed” / Bot ignores you

Cause: Your User ID isn’t in MATRIX_ALLOWED_USERS.

Fix: Add your User ID to MATRIX_ALLOWED_USERS in ~/.hermes/.env and restart the gateway. Use the full @user:server format.

Security

:::warning Always set MATRIX_ALLOWED_USERS to restrict who can interact with the bot. Without it, the gateway denies all users by default as a safety measure. Only add User IDs of people you trust — authorized users have full access to the agent’s capabilities, including tool use and system access.

::

For more information on securing your Hermes Agent deployment, see the Security Guide.

Notes

• Any homeserver: Works with Synapse, Conduit, Dendrite, matrix.org, or any spec-compliant Matrix homeserver. No specific homeserver software required.
• Federation: If you’re on a federated homeserver, the bot can communicate with users from other servers — just add their full @user:server IDs to MATRIX_ALLOWED_USERS.
• Auto-join: The bot automatically accepts room invites and joins. It starts responding immediately after joining.
• Media support: Hermes can send and receive images, audio, video, and file attachments. Media is uploaded to your homeserver using the Matrix content repository API.
• Native voice messages (MSC3245): The Matrix adapter automatically tags outgoing voice messages with the org.matrix.msc3245.voice flag. This means TTS responses and voice audio are rendered as native voice bubbles in Element and other clients that support MSC3245, rather than as generic audio file attachments. Incoming voice messages with the MSC3245 flag are also correctly identified and routed to speech-to-text transcription. No configuration is needed — this works automatically.